The Experimental Hydration of Obsidian as a Function of Relative Humidity and Temperature
| Autor: | J. K. Bates, C. M. Stevenson, W. L. Ebvert, J. J. Mazer |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
010506 paleontology
Archeology History Materials science 060102 archaeology Museology Obsidian hydration dating Analytical chemistry Mineralogy 06 humanities and the arts 01 natural sciences Isothermal process Arts and Humanities (miscellaneous) Potential difference 0601 history and archaeology Relative humidity Water diffusion 0105 earth and related environmental sciences |
| Zdroj: | American Antiquity. 56:504-513 |
| ISSN: | 2325-5064 0002-7316 |
| DOI: | 10.2307/280898 |
| Popis: | The experimental hydration of obsidian for up to 30 days is described at relative humidities (RH) of 60, 90, 95, and 100 percent and at temperatures of 150, 160, and 175°C. Under isothermal conditions, the rate of hydration increased by as much as 25 percent between 60 and 100 percent RH. The RH dependence is nonlinear, with the majority of the rate increase occurring between 90 and 100 percent RH. The effect of RH can be related to the driving force for molecular water diffusion in obsidians as described by the chemical potential difference between water sorbed onto the obsidian surface and intrinsic water in the obsidian. The differences in hydration rates caused by RH differences in experiments approximate the error commonly described for obsidian-hydration dating. These results suggest that obsidian-hydration dating requires a knowledge of the site temperature and relative humidity in order to accurately generate age estimates. |
| Databáze: | OpenAIRE |
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